Ti83 LEDs

[theshadow27]

this is a transcript of a thread out of Xoxide Fourums... im bringing it here because you guys tend to know a little bit more (read: a hella lot more) then anyone over there. just looking for some feedback. ~theshadow27

okay im prototyping a tutorial here. its how to add an LED/LEDs to your TI83 witout a switch/external power.

lets start with the basics... if you cant open the case then you shouldent be in the modding fourm. once open, it becomes aparent that TI did a great job of making the keypad almost 1 piece, making the back come off easy, and haveing the whole thing put together just all around very well.

this is a special edition ti83 (not plus) for my experements. im not gonna take apart my silver edition untill i have a decent plan.

4 AAA bats spits out ~6v when brand new. i figure it should run off 5:

looks like it does.

now some more pics... this will eventualy become a LCD for my comp, so ill start with the obious:

next lets get some pic's of the chips. they are going to be the key here:

the numbers on them read:

MX
C001738
1P1488A4

and

Toshiba
T6C79

and

Epson
F99512277
SRM2B256 2LN MX70

next up is figguring out what each chip is, and what it does. the reason that they are so important is this: the calcuator doesnt have a relay in it that phisicly shuts off power with the on button. all the chips remain running and powerd when it is off (i have verifyed this with da scope). they are in sleep mode... activated by a pin being pulled low/high. what pin it is, and who does the pulling is yet to be determinded. but once it is, you can slap a SMT transistor on there and power up to 10 LEDs off a TTL signal.

the TI that is currently being examined is totaly diffrent from my TI-83+SE. ive gotten a lot of usfull info from this site: http://www.datamath.org/Sci/Modern/TI-83PLUS_SE.htm . but im going to need a backlight for my computer's display anyway, so im gonna keep pushing this till i figure it out.

here is waht i know so far:

the biggest chip is the ASIC prossesor (good call jpritchard). then we have a 'ROM' chip from Epson (realy EEPROM), and a display driver chip.

some other (important) parts that ive highligthed are the main pullup resistor rated at a half a watt (enugh to reasonably supply leds...) and the main filter cap, that has ground and positive in the same place.

okay... next update:

the dotmatix display driver:

(the number is printed on it) is pretty cool, and fairly well doccumented. the data sheet is here. according the the data sheet, the 13th pin in from the left is /stb (standby) that puts the chip into low-power (off) mode. i figured that this would probably be used to turn off the screen when the calculator was "off" (standby mode). so i hooked up my scope, and vwala! it is . so i hooked an LED up to it. and agien, on with calc, off with calc.

the screen is hooked up with a SM (surface mount) ribbon cable, which is exceedingly diffucult to solder to. so i hooked up my florecent illuminator box (i made it for blueprinting, but its great for PC board traces) and got out my exacto knife (to scrape away silkscreen). it happens to go to a end pin on the prossesor! lucky me.

next update, im going to hook up a transistor to it, and ill show yall how to do it. then the transistor will drive a couple LEDs to backlight the screen. then ill dig into my favroite TI-83+SE and do the same mod, but ill take more pictures.

anyway. for all of thos new to SurfaceMount, and that are scared to use there big ass soldering iron on anything tiny, check this out:

i used a 6$ radioshack iron just to prove its possable.

next your gonna want a small dab of glue (i like hot glue, its cheap, easy to get off if you mess up):

now for the LED. because this isnt clear, i needed a good place to put it. how bout the power button?

lets do some sanding...

and finish it up with mona lisa "superfilm" (awsome stuff i found at michals):

alright lets put it all back togheter for a test fit:

hope you guys like it so far... im not gonna post the wireing yet because im gonna do some intensive testing to make sure it doesnt mess anything up.

 

[KoZLop]

I use the same calculator for school.


Nice mod though..

 

[Grizzy]

Wow, awesome. Is it possible to use theti-83 screen as a computer screen type thing for winamp visualizations and things? Backlit, that would be great. You will definately have to post a more detailed set of instructions when you get done, I am eager to cut up mine since I rarely use it anymore

 

[theshadow27]

yeah this whole project started when i _found_ a couple of extra TIs lying around at school... the first thing that i thought was "this is a bigger screen then any (non graphical) LCD ive seen on a comp". as i was posting pics of the disection on Xoxide, someone asked me if i could write a tut on how to add LEDs. so im doing that first.

as for the LCD, i started by seeing if you could feed it data thrugh its "link port" but they are using a propriatary protocal that i dont even wana play with. the LCD has its own driver chip built onto the back of it, and its only a 32 pin SM interface (better then mesing with the 300 something LCD pins), of witch there are 6 data lines. it would be pretty easy to write my own LCD instructions, and throw together a board to control it.

also in the works... backlighting (leds arnt bright enugh to do it, the screen is too big) with a built in EL inveter (unlike http://michaelv.org/calc_mods.php i would fit the inverter inside of the case).

 

[Impulse]

Texas Instruments sell their own cable for hooking up the TI-83s to your PC... I remember ordering one back in high school (the whole intent back then was to load the TI-83 shock full of games, heh, had everything from Tetris to Space Invaders going on).

Was a Serial kit, came with it's own software. Anyway, the software it came with would even let you program within the computer for the calculator (the same way you do it in the calculator, 'cept also allowing amenities such as copy/paste, etc.).

Making it display whatever you want is not hard at all, making it react to computer events and/or read data from the computer to output would require some extra coding/software tho.

 

[theshadow27]

Texas Instruments sell their own cable for hooking up the TI-83s to your PC... I remember ordering one back in high school (the whole intent back then was to load the TI-83 shock full of games, heh, had everything from Tetris to Space Invaders going on).

Was a Serial kit, came with it's own software. Anyway, the software it came with would even let you program within the computer for the calculator (the same way you do it in the calculator, 'cept also allowing amenities such as copy/paste, etc.).

Making it display whatever you want is not hard at all, making it react to computer events and/or read data from the computer to output would require some extra coding/software tho.

yes the cable is called the "graph link" and i have a bunch of them. they do not have provisions for real-time communication, only for file transfer. i could have it send a text file every second, but that would be a pain.

it would be a lot easier (for me) to drive the LCD my self

 

[aL Mac]

how much current at what voltage do those EL panels pull ?

what's the LED for ? I don't see the point.. but nice job. I would think the backlight internally would be cool, but from the 86 page it looks really really easy to screw up something. I would like to see a backlight on an 89 then I'd do one myself so I can do my math/physics in the dark! =)

 

[aL Mac]

actually just went to the EL panel site and it says 2 AAA batteries so I assume 3 V? any idea on how much current it pulls and how long it would last on those batteries?

EDIT: How do you plan on fitting the inverter in the case.

edit2: do you plan on the backlight always on with the on button? possibly you could mod a small switch on the side for it where the other guy had the prongs coming out. I'd say.. have it turn on with the on button when the switch is on.. or you can turn the switch off for it to be off. Just a very small switch mounted on the side

 

[theshadow27]

as for the point of the LED: it was a proof of concept as to where i could tap the sleep/awake signal.

the EL inveter that i bought for this runs off of 3v and will run on a pair of AAA batts for about 8 hours. my for the switch is to have the first power button press turn on the calc, the next press turn on the EL, and the next press turn off the EL. or i could put a small switch in, but thats no fun.

where to put the inveter: there is foam that holds the screen flush agenst the case. if you take all the crap out of the battery inverter, the board is less the 1 inch x 1 inch x 2mm. i would cut out some foam and put it there. possably drill some holes in the back for air.